There has been proposed a gas turbine engine having an exhaust diffuser for guiding exhaust air or combustion gas from the turbine. Typically, the diffuser has a double cone structure made of an inner cone, and an outer cone arranged coaxially with the inner cone to define an annular exhaust channel between the inner and outer cones (see, for example, JP 2004-197696 A). The exhaust channel is fluidly connected to the downstream end of the annular turbine channel, so that the combustion gas from the turbine channel is guided through the exhaust channel into the atmosphere.
The exhaust combustion gas has a high-temperature. This requires a suitable cooling arrangement for protecting molded structural components, such as supporting components or bearing box, disposed within a central cavity surrounded by the inner cone from being thermally affected by the high-temperature exhaust air.
Accordingly, a purpose of the invention is to provide a highly reliable gas turbine engine in which the structural component or components mounted within the central cavity surrounded and defined by the exhaust diffuser are cooled effectively.